Bifocal and Multifocal Contact Lenses for Presbyopia and Myopia Control

Abstract

Bifocal and multifocal optical devices are intended to get images into focus from objects placed at different distances from the observer. Spectacles, contact lenses, and intraocular lenses can meet the requirements to provide such a solution. Contact lenses provide unique characteristics as a platform for implementing bifocality and multifocality. Compared to spectacles, they are closer to the eye, providing a wider field of view, less distortion, and their use is more consistent as they are not so easily removed along the day. In addition, contact lenses are also minimally invasive, can be easily exchangeable, and, therefore, suitable for conditions in which surgical procedures are not indicated. Contact lenses can remain centered with the eye despite eye movements, providing the possibility for simultaneous imaging from different object distances. The main current indications for bifocal and multifocal contact lenses include presbyopia correction in adult population and myopia control in children. Considering the large numbers of potential candidates for optical correction of presbyopia and the demographic trends in myopia, the potential impact of contact lenses for presbyopia and myopia applications is undoubtedly tremendous. However, the ocular characteristics and expectations vary significantly between young and older candidates and impose different challenges in fitting bifocal and multifocal contact lenses for the correction of presbyopia and myopia control. This review presents the recent developments in material platforms, optical designs, simulated visual performance, and the clinical performance assessment of bifocal and multifocal contact lenses for presbyopia correction and/or myopia progression control.

Figure 1

Illustration of different contact lens designs. In red: areas for near vision; in blue: areas for distance vision.

Figure 2

Illustration of the power maps (left), the proportion of the total pupil area covered by the distance and near correction as a function of the pupil diameter (center), and the through-focus Visual Strehl for pupil diameters of 4 mm and 6 mm (right) of different simultaneous image multifocal and bifocal contact lenses: (a) Acuvue Oasys for presbyopia, (b) Dual Focus, (c) PV: Purevision and (d) Airoptix (redrawn from Plainis et al. [37]). Profiles are designed to provide a distance correction power of −3.00 and an addition power of +2.00 diopters resulting in −1.00 of near correction power.

Figure 3

Illustration of the phase pattern and through-focus theoretical simulations of the Snellen E-letter of 30 arc-min for 4 mm pupil diameter (from −1.5 to +1.5). Top: diffraction-limited eye; bottom: aspheric-based design (spherical aberration: +0.25 μm).

Figure 4

Through-focus Visual Strehl for the theoretical diffraction-limited eye (dashed) and the aspheric design (solid) for 4 mm pupil diameter and different light level conditions: 1000 cd/m², 10 cd/m², and 1 cd/m². ^∗ Threshold for acceptable vision.

Figure 5

Reconstruction of the binocular defocus curves drawn at the same scale from different studies: red line: 20 subjects (49–67 years of age) fitted with Softlens multifocal (Gupta et al. [99]). Blue line: 20 subjects (age: 45–63 yrs) Proclear Toric Multifocal (Madrid-Costa et al. [113]). Orange line: 20 subjects (age: 42–48 yrs) Acuvue Oasys (Madrid-Costa et al. [102]). Green line: 20 subjects (age: 42–48 yrs) Acuvue Oasys presbyopia (Madrid-Costa et al. [102]). Black line: 38 subjects (age: 48–62 yrs) Proclear Multifocal (Garcia-Lázaro et al. [116]). Dashed grey line: expected performance for fully presbyopic eyes (unpublished data from CEORLab-UMinho).